Pandora has the honor of being the first woman on earth. And boy does she gum up the works. By opening the forbidden jar, she releases every bad thing ever onto mankind, and gives us what we now know as horrible suffering. Thanks, Pandy!
Who's to Blame
Of course, can you really blame her? After all, she was designed by Zeus to do this very thing; she doesn't really have a choice in the matter. Reading the myth the 21st century, we might say "he just wanted to blame a woman, that misogynistic pig!" But you have to remember, feminism wasn't around back then, so the Greeks probably weren't too worked up about it. Also, when you call Zeus a misogynistic pig, he gets kind of angry.
Whatever the case, Pandora is the one who opens that box, so she's the one we associate with the disaster, even to this day. If you ever hear someone say "you've really opened a Pandora's box with that one," you know you've messed up. Just keep your fingers crossed that there's a little hope left for you, too.
Some nerdy folks in mythology departments think that the version of Pandora in this story is actually a distortion of an even earlier myth, in which she was an all-giving earth goddess. That would account for the negative portrayal of Pandora in this version—it might just be a symptom of growing male oppressiveness in Greek society.
If the story sounds familiar and you haven't heard this earth-goddess version, you might want to pick up your copy of the Bible. Back in Genesis, the story of Adam and Eve sounds pretty similar… don't you think?